#!/usr/bin/env sh

set -eu

firmware="#FIRMWARE#"
terms_url="https://www.microsoft.com/en-us/legal/terms-of-use"

skip_disclaimer=0

usage() {
    echo "Usage: $(basename "$0") [OPTIONS]"
    echo
    echo "Downloads the firmware required by xow. Saved as $firmware"
    echo
    echo "OPTIONS"
    echo
    echo "  --skip-disclaimer"
    echo "        The firmware is covered by the Microsoft Terms of Use:"
    echo "        $terms_url"
    echo
    echo "  --help"
    echo "        This help screen"
}

parse_args() {
    while [ $# -gt 0 ]; do
        case "$1" in
            --skip-disclaimer ) shift; skip_disclaimer=1;;
            -h | --help ) usage; exit 0;;
            * ) usage; exit 1;;
        esac
    done
}

fail() { echo "$1" >&2; exit 1; }

check_program() {
    [ -x "$(command -v "$1")" ] || fail "Cannot find $1 - required to $2 the firmware."
}

check_root() {
    [ "$(id -u)" -eq 0 ] || fail "You have to be root to run this script."
}

check_programs() {
    check_program "curl" "download"
    check_program "cabextract" "extract"
}

disclaimer() {
    echo "The firmware is distributed under the Microsoft Terms of Use:"
    echo "$terms_url"
    echo
    printf "Do you accept the terms of the agreement? [y/N]: "

    while true; do
        read -r option
        case "$option" in
            Y|YES|y|yes) break;;
            N|NO|n|no|'') fail "You must agree with the terms in order to continue. Exiting.";;
            *) echo "Please answer yes or no.";;
        esac
    done
}

get_firmware() {
    url="http://download.windowsupdate.com/c/msdownload/update/driver/drvs/2017/07/1cd6a87c-623f-4407-a52d-c31be49e925c_e19f60808bdcbfbd3c3df6be3e71ffc52e43261e.cab"
    sum="48084d9fa53b9bb04358f3bb127b7495dc8f7bb0b3ca1437bd24ef2b6eabdf66"
    cwd=$(pwd)
    tmp=$(mktemp -d)

    cd "$tmp" >/dev/null 2>&1

    curl -L -o driver.cab "$url"
    cabextract -F FW_ACC_00U.bin driver.cab
    rm driver.cab

    echo "$sum" FW_ACC_00U.bin | sha256sum -c

    destdir=$(dirname $firmware)
    [ -e "$destdir" ] || mkdir -p "$destdir"
    mv "$(pwd)"/FW_ACC_00U.bin "$firmware"

    cd "$cwd" >/dev/null 2>&1
    rmdir "$tmp"
}

main() {
    parse_args "$@"
    check_root
    check_programs
    [ $skip_disclaimer -eq 0 ] && disclaimer
    get_firmware
}

main "$@"
